Blended Polymer Composition with Enhanced Elasticity
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Solution Overview
Problem
Current methods for producing high molecular weight polymer compositions with metallocene catalysts face challenges in achieving high molecular weight distribution and enhanced elasticity, particularly in avoiding the formation of in-reactor gels and maintaining reactor performance.
Innovation Solution
A method involving the blending of vinyl-terminated polymer (VTP) and high molecular weight polymer (HMP) compositions, where the VTP composition is produced with a VTP catalyst compound and the HMP composition is produced with an HMP catalyst compound, and then combined to achieve a blended polymer with enhanced elasticity, utilizing specific catalyst systems and activators to control molecular weight and rheological properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If dienes are added to the polymerization process to produce long-chain branched polyolefins, then the elasticity of the polymer composition is improved, but insoluble gels are formed when the level of branches becomes too high
Solution Approach 1:
The patent changes the chemical parameters of the polymerization process by using specific metallocene catalysts (catalyst systems A and B with different structures) to control the degree and type of branching. This allows achieving high elasticity through long-chain branching while preventing excessive branching that would lead to gel formation. The catalyst structure parameters are optimized to achieve the desired balance.
Solution Approach 2:
The patent produces a composite polymer composition containing both linear polyolefin and long-chain branched polyolefin components with controlled molecular weight distributions. This composite structure achieves enhanced elasticity while maintaining solubility and avoiding gel formation by distributing the branching throughout the polymer matrix rather than allowing localized gel formation.
2Stability of the object's composition
If the molecular weight of the polymer is increased to enhance elasticity, then the viscosity at low shear rates is improved, but the extrusion throughput decreases due to high viscosity
Solution Approach 1:
The patent utilizes the shear-thinning property of long-chain branched polymers by controlling the molecular weight and branching density. At low shear rates (during storage and compounding), the high viscosity provides stability and elasticity. During extrusion at high shear rates, the viscosity decreases due to shear thinning, maintaining high throughput. This parameter optimization resolves the contradiction between elasticity and productivity.
3Object-generated harmful factors
If macromonomers are used to create long-chain branched polyolefins, then in-reactor gel formation is avoided, but the level of incorporation is low due to the lower molar concentration
Solution Approach 1:
The patent uses metallocene catalysts with specific molecular structures and activation systems to dramatically increase the activity and incorporation efficiency of macromonomers. By optimizing catalyst parameters (ligand structure, metal center) and reaction conditions, the patent achieves high levels of macromonomer incorporation (sufficient to produce significant long-chain branching) without the gel formation problems associated with traditional diene-based methods.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The blended polymer composition exhibits improved rheological properties, including high viscosity at low shear rates and low viscosity at high shear rates, with a molecular weight distribution that supports enhanced elasticity and stability, effectively addressing the limitations of existing metallocene-based processes.
Implementation Method 1
employing VTP and HMP catalyst systems in parallel processes
Data Source
AI summary
Provided herein are methods of making blended polymer compositions having enhanced elasticity. The present methods comprise the steps of producing a first polymer composition using a VTP catalyst system, producing a second polymer composition using a HMP catalyst system and combining the first polymer composition and the second polymer composition to make the blended polymer composition. The present methods include blending/combining the polymer compositions produced by different catalyst systems. One such catalyst system includes (i) a vinyl-terminated polymer (VTP) catalyst system comprising a VTP catalyst compound (referred to herein also as a “VTP catalyst”) and one or more activators. Another catalyst system includes a high molecular-weight polymer (HMP) catalyst system comprising a HMP catalyst compound (referred to herein also as a “HMP catalyst”) and one or more activators. The activators of these different catalyst systems can be the same or different in whole or in part.